[postgis-devel] [PostGIS] #791: Topology: function GetEdgeByPoint($1, $2, $3)

[PostGIS]

#791: Topology: function GetEdgeByPoint($1,$2,$3)
-------------------------+--------------------------------------------------
 Reporter:  aperi2007    |       Owner:  strk         
     Type:  enhancement  |      Status:  new          
 Priority:  medium       |   Milestone:  PostGIS 2.0.0
Component:  topology     |     Version:  trunk        
 Keywords:               |  
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Comment(by nicklas):

 Hallo

 I don't know the ST_Intersects algorithm but the problem for ST_Dwithin is
 that the faster way of doing it in 1.5 will not be used in the cases where
 the bounding-boxes intersect. In the case of using ST_DWithin as a
 intersection test the faster algorithm will never get used because the
 cases with no intersecting bounding boxes will be sorted away already by
 the index.

 So, until Paul implements his indexing of vertexes in
 distance/intersection presented
  here [http://postgis.refractions.net/pipermail/postgis-
 devel/2009-December/007710.html]
 and here
 [http://blog.cleverelephant.ca/2009/11/is-good-enough-good-enough.html]

 until then, I am afraid we will have to live with the brute force way of
 doing the calculation for ST_DWithin(geoemtry, 0)

 But what I enhanced in 1.5 was also that I put in a lot of more "Is the
 answer already given" tests, which might give quite a lot better
 performance in those cases. Before 1.5 this was only tested once per
 interior ring.

 strk, do you have insight in ST_Intersects algorithm?

 Regards
 Nicklas

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/791#comment:9>
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